A ferrite film known in the art is used as a noise reduction material to reduce unnecessary radiated electromagnetic field noise from an electronic component and a core material to stably increase the inductance of a substrate-incorporated coil (inductor). The ferrite film is expressed by the composition formula of MxFe3-xO4, where, for example, Ni, Zn, Co, or the like is used as M. International Patent Publication No. 2004/099464, Japanese Laid-Open Patent Publication No. 2006-108557, and Japanese Laid-Open Patent Publication No. 2004-107696 describe examples of ferrite films in the art.
A ferrite film that includes a number of metals other than iron such as nickel and zinc easily obtains the desired electric and magnetic characteristics. However, it is difficult to control reactions during the formation of the ferrite film. In this regard, a zinc ferrite film that includes only zinc in addition to iron allows reactions to be easily controlled during the formation of the ferrite film and is thus suitable for mass production. However, it is difficult to obtain the electric characteristic or magnetic characteristic required for a noise reduction material and a core material.